In the liner notes to this recording, the Helianthus Ensemble declares a desire to combine musical performance with ‘didactic work’, and to demonstrate the continuing relevance of eighteenth-century music. They succeed here on both counts, delivering a technically accomplished and musically compelling performance of C. P. E. Bach's chamber music, along with a useful, if brief, scholarly introduction to his quartets for flute, viola and obbligato keyboard.

Founded by flute player Laura Pontecorvo, the Helianthus Ensemble initially focused on exploring seventeenth-century chamber repertoire for flute; this CD represents their first release of eighteenth-century music, timed to correspond with the tercentenary of Philipp Emanuel's death. Although the recording includes a trio sonata and duet, Bach's quartets in A minor (Wq93, h537), D major (Wq94, h538) and G major (Wq95, h539) are clearly intended to be the showpieces here. These works constitute Bach's only contribution to the quartet genre, and while they have not garnered the kind of fame now attached to the string quartets of his contemporary Joseph Haydn, they remain far from forgotten. In fact, they are favourites among traverso players, and receive regular performance today. Fans of this music have a number of important recordings from which to choose, including those by Nicholas McGegan (L’Oiseau-Lyre DSLO 520, 1977), Wilbert Hazelzet (with Ton Koopman, Philips 416 615, 1983; and Les Adieux, EMI/DHM 88697959572, 1988), Konrad Hünteler (Ex Libris 6021, 1985), Philippe Allain-Dupré (Mandala 4922, 1998) and, most recently, the Kuijken brothers (Accent ACC24293, 2015).

While this therefore represents something of a crowded field, few would dispute that the quartets are deserving of such attention, and the generally excellent liner notes supplied by Pontecorvo (translated by Kate Singleton) do a good job of contextualizing these works for modern audiences. Composed in the final year of Bach's life (1788), these are formidable works, offering substantial technical challenges for all members of the ensemble. Pontecorvo makes a point of noting that the quartets were produced at a time when Bach was particularly concerned with his legacy as a composer and was, on the whole, less focused on producing work to satisfy the amateur market; these are works, then, that lean decidedly toward the tastes and abilities of Kenner, rather than Liebhaber. In addition to the technical challenges they pose, the quartets have also been singled out by David Schulenberg as works in which Bach's skills as a ‘Fantast’ were at their virtuosic height (Schulenberg, The Instrumental Music of Carl Philipp Emanuel Bach (Ann Arbor: UMI, 1984), 6–7). True to the fantasia style for which Philipp Emanuel was best known in his day, these works showcase abrupt dynamic shifts, unusual tonal patterns, pseudo-improvisatory passagework, interruptive phrase structures and, above all, an ever-shifting palette of affects and character types. Convincingly rendering such extreme changes on the one-keyed flute, particularly when it comes to the exploration of distant tonalities and large dynamic contrasts, is no small feat.

Pontecorvo also does a good job of clarifying the most famous performance-practice issue that these works raise. In the posthumous catalogue of Bach's estate, the Nachlass-Verzeichnis of 1790, they are entitled ‘Quartetten’ and described as being for flute, viola, Clavier and bass. But the manuscripts themselves, now preserved in Brussels and Berlin, include no separate bass parts, and are simply called ‘Quartetti per il Cembalo, Flauto traverso e Viola’. This has led some – including the organist Johann Jacob Heinrich Westphal in the 1790s – to wonder whether parts for cello were originally intended and have since gone missing (see letter of Anna Carolina Bach to Westphal of 7 October 1791, in Stephen L. Clark, ed., The Letters of C. P. E. Bach (Oxford: Clarendon, 1997), 84). Modern scholarly consensus, however, is that the nomenclature ‘quartet’ referred in this case to the number of obbligato parts and not necessarily to the number of instruments or performers involved. While the addition of cello to the ensemble is certainly plausible, then, performing the works with only a flute, viola and keyboard – which plays composed right- and left-hand parts, rather than an improvised continuo realization – is thus a perfectly valid possibility (Schulenberg, Instrumental Music, 166, note 11). This is the configuration in which Helianthus performs them, claiming that this ‘enhances the balance and clarity of the musical discourse’ (liner notes, page 3) – perhaps because it reduces the stiff competition the traverso already faces in being heard.

Despite the explicitness with which Pontecorvo justifies this performance decision in the liner notes, she does not offer insight into other interesting (if much less controversial) choices made by the group, such as their decision to use harpsichord rather than fortepiano, or her own use of a reproduction of a flute by Carlo Palanca. This is in not to impugn the validity of these decisions, but given the ensemble's professed didactic intent – together with the fact that one of the primary audiences for such recordings is constituted by those with a keen wish to learn how to play early instruments – the inclusion of such information would have been most welcome. Her rationale for choosing a Palanca flute would no doubt be of particular interest to today's growing ranks of amateur and pre-professional baroque flute players, many of whom in the last ten years have taken up reproductions of this particular instrument as a kind of universal one-keyed flute because of its relatively loud sound, strong cross-fingered notes and easy high register. It is indeed precisely these sonic characteristics that make the instrument particularly useful for attempting the challenging late works of C. P. E. Bach; on the other hand, its elliptical embouchure hole makes the Palanca flute anomalous in the eighteenth century, and Palanca himself seems at times to have been thought of as producing instruments of questionable quality (John Spitzer and Neil Zaslaw, The Birth of the Orchestra: History of an Institution, 1650–1815 (New York: Oxford University Press, 2004), 173). At the very least, then, players who hope to follow Pontecorvo's example in playing this music will have to confront the decision of whether to use a Palanca as she does, one of the more readily available one-keyed Grenser reproductions, or even a four-, six-, or eight-keyed flute such as was already in common use by the 1780s.

The quality of playing here is very high, and this recording certainly ranks with Hazelzet's as one of the best available for this repertory. Throughout the three quartets, the ensemble very successfully brings off the rapid changes in character of Bach's music; indeed, it is a rare luxury to hear such satisfyingly clear shifts between forte and piano. Pontecorvo offers up a lovely range of articulations over the course of the recording, from extremely delicate to direct and pointed. She does an excellent job of leveraging this articulatory variation, together with agogic accents and actual differences in volume, in order to give the impression of an uncommonly wide range of dynamics.

The A minor quartet, which opens the recording, announces immediately the impressive ensemble playing of which this group is capable. Melodies in the first movement are passed smoothly and rapidly between keyboard, flute and viola, and the group as a whole does a good job of both navigating and bringing sense to the many metrical shifts of the third movement. Notwithstanding a few subtle disagreements between members of the ensemble with respect to the timing of some ornaments in the second movement, one has the impression that this is an extremely well-thought-out rendition.

The fast passagework in all parts sounds light and relaxed – at times even languorous – betraying little sense of the considerable technical challenge it poses. The group plays the third movement as a true allegro assai, yet succeeds in including many fine nuances. Violist Elisa Citterio and harpsichordist Guido Morini produce, for example, beautiful tapers at the ends of phrases – even though, at this tempo, such moments positively fly by. And Pontecorvo's runs are extremely accurate and clean throughout, interspersed occasionally with well-chosen slurs or changes in the pattern of articulation designed to clarify the melodic contour. The one moment to disrupt the overall sense of technical ease engendered by the group's performance is Pontecorvo's decision to close the first movement by playing the final two notes (marked ad. lib.) up the octave, at the very top of the baroque flute's range. While this certainly provides an emphatic ending, and she plays these notes (a high G♯ and A♮) impressively well in tune, their strained timbre nevertheless produces a jarring effect that disrupts the fluidity with which the rest of the quartet is played.

The other quartets are played with equal skill. Although the performers underplay the two-note sighing figures that pervade the first movement of the D major quartet, the many unison melodies between the flute and harpsichord are again very well in tune. Tricky rhythmic passages here and throughout the G major quartet are extremely well together, despite the rapid shifts of motivic work between all three parts. The Adagio of the G major quartet is notable for being played faster, and with considerably less rubato, than some renditions; their performance is by no means pressed, but leaves relatively little silence between the many short phrases, effectively avoiding the trap of becoming dirge-like. Nevertheless, it offers plenty of contrast with the subsequent Presto, which tears along with almost continuous semiquaver runs. As elsewhere, the ensemble is tight: both the flute and viola do an excellent job of staying in time on entrances that begin repeatedly on the second semiquaver of the beat, and their articulation is neat and clear throughout. Theirs is an enviably easy-sounding virtuosity.

While the quartets have received a great deal of attention since the 1980s, the third work on this disc, Bach's Duet in E minor for flute and violin (Wq140, h598) is arguably in greater need of being brought to the attention of music lovers. This work remains little known today, and good performances such as this are most welcome. Unfortunately, Pontecorvo pays the work little attention in the CD liner notes, other than to mention – somewhat ambiguously and without further explanation – the ‘ironic’ nature of its third movement. She moreover fails to note that the duet represents a significant departure from the quartets that otherwise form the main focus of this recording, insofar as it was explicitly published for amateur musicians in Bach's 1770 collection of Musikalisches Vielerley.

This is not, however, to bring into question the quality of the duet as a work, nor the conviction with which Pontecorvo and Citterio play it. The two share an obvious affinity: in a texture that offers no place to hide, they are well attuned to one another's intonation and choices in timing. They do an excellent job of giving the long, languid phrases of the first movement direction without hurrying each musical thought to its end, and they render layered entries of semiquaver runs precisely throughout. Ornamentation added to the repeats in the second and third movements is tasteful, and clearly well planned between the performers. Citterio is sensitive to the dynamic levels of the flute as an instrumental partner throughout this recording. But one wonders whether, in the duet, the flute was placed closer to the microphone in order to improve balance, since considerably more background air noise is audible, while reverb is less apparent. The resulting aural impression is that Pontecorvo seems much closer than in the quartets.

The A major trio sonata (Wq146, h570/542) that closes the disc is, like the quartets, a well-known favourite amongst flute players. And like the other works on the recording, the ensemble plays it well; flute and viola are again strikingly well synchronized. Pontecorvo does an excellent job with the intonation of cross-fingered notes, of which this trio is full (particularly in its flirtations with difficult keys like F sharp minor). And she more than holds her own in terms of producing sound in the low register, particularly around the ever-problematic low G♯s. But like the duet, the trio sonata feels like something of an outlier on this recording: although it closes the CD, it is stylistically much earlier than the rest of the featured repertoire. In fact, it dates from Bach's time in Leipzig more than half a century before (c1731). While the melodic lines are full of triplet figuration, the work's musical language is on the whole much less brilliantly virtuosic, semi-improvisatory and fantasia-like than the quartets. It differs too insofar as it features many walking bass lines and, in places, a Trommelbass (drum bass) – that typically galant device featuring rhythmic repetition of pitches in the bass even when the harmony remains static for many beats. And, like the duet, it occasions very little commentary from Pontecorvo. At best, then, the work risks seeming somewhat out of place here, especially as a closer. At worst, it risks being read as mere filler material – included as a simple adjunct to the quartets, which occupy the true centre stage. Such a treatment is distinctly at odds with the beauty of the work itself – and surely with the very compelling fashion in which the Helianthus Ensemble performs it. A reordering of the works on the disc, or a more thorough treatment in the liner notes, would have prevented this work from feeling like an afterthought.

Such minor reservations aside, however, this is a first-rate recording, and on the strength of the musicians’ performances alone it represents an impressive contribution in a field already populated by some of the biggest names in baroque flute-playing. Those interested in exploring both the more famous chamber works for flute of C. P. E. Bach, and lesser-known pearls such as the duet, will find it worthy of much-repeated listening.